Electronic switching device



March 13, 1951 GROSDOFF 2,545,082

ELECTRONIC SWITCHING DEVICE Filed May 28, 1946 2 Sheets-Sheet 1 IN VEN TOR.

BY M4 may Mmh 13, 1951 v I, E. G OSDOFF 2,545,082

ELECTRONIC SWITCHING DEVICE Filed May 28, 1946 2 Sheets-Sheet 2 INVENTOR.

Ear l. Grosdof'f .4 i for fley- Patented Mar. 13, 1 951 Igor Grosdofi, ,Princeton, J assignor; to.

Radio Co orat on o Ame aac r at n ofDelaware Application May 28, 1946, Serial Nd: 672,748

1.01 m. v(o1. 250-27) n ention. relates a to e ectronic sw tching M r pa t cularly. itpr vid s an imdevices. proved switching devicena-nd method of qoperation wh by n. c rical c rcuit may be pened o closed with n a time interval whichi oi hfi'fir fil" of one hundred millionth oi a second 0.9 sec). The. invention is illustrated herein as utilized to co tr th dmiss on of-h h fr y ul s to a counter by which'the number of admitted pulses is indicated. it hasqutility in various other cases where high Speed switching Operations are involved.

When utilized to control the admission of high frequency pulses to a. counter, the improve switching device of the presentinyention inay be regarded as a mixeroftwo unrelated signa1s ,..o,ne. signal being the pulses tonbe countedand the.

other signal being the start and stop pulses .dee fining. the interval during which thecountis. .to

takeplace. Undertheseconditions, the pulses to.

be counted are passed througha gate which is openedand closed in response to the start and.

stop pulses. This gate may, bein the form of. a space discharge device such as a-triode which is made conductive by the startpulseand is non-conductive by the stop pulse.

In order that the counting of the pulses be accurately timed, it is essential (1) that the opening and closing times of the gate be shorter than-the period of the counted pulses and (-2)' that the counter be unaffectedby the switching pulses. As the frequency of theicounted pulses increases and as the time of the count decreases, the necessity of rapid opening and closing of the gate increases. In accordance with the". present invention, such rapid opening and closing .of gate is effected by means of electron discharge devices of the gaseous --.conduction type which are. substantially instantaneous their response to the timing. or start and stop, pulses.

Heretofore a square wave representing: the time of the count has been produced by trigger circuits of the multivib'rator type. It. iswell known that the time required for such atrigger circuit to change from one of its stable conditions to the other is finite and that they square wave which it produces has .difierent slopes at its opposite ends. This is especially notable .at the end of the wave where a free discharge is taking place for the reason that the sharpness of the wave front at this point depends on the RC constant of the diSQha-rge circuit. Such time lag in the operation of the gate and such difference in the slope at the opposite ends of the timing wave are likely to result in the skipping 2 of pulses that should be indicated by the counter-.;

In accordance with t ep esentin entiens diffi ulty s avoided by t e: pmr en hi discharge device or'triode which (1) z unctiensas.

the gate throu h whi h the puls s t b counted are pa s to. the cou te and (.2) as ductivitycontrolled by .gaseouscond tie :.B1 G.r-

tron dischar eelemeet ene-ci w r sume 9' the start pulse and the gtheret whieh respends: to th s opulse This insu s substantiate i stant neo s e e icn or the: a e f r the eas n h uc cases se ment pond i a ime of the orde ei 1 ecmdha aw y low impe an a er he begin t ma n thus per t ing d schar e 10 th ass ei ed @aP. itQr-- t an ex mel IaP d at-- Th p nc e ie ifhe r sen i en en is-to..p;royide an -i nproved electronic switch and method pf operation whereby an electrical vcinuit ay be e dand l sed w heutap iame time l vlnor an o iec s of the vention arethe provision pf an improved-'swit ins c u fe o l ne he supp ofm to a-counter, and the provisionef aswitchha.

.5" e al el m n s h ch a esubstantial y instanane a t onlheih e t on w ll babettc nd r's'ts -Qd h -fo owing de xi ti ro is d ed tier: with he a ccmnanyinefirair nss and its: ene-i in ica ed :bythe a pended clans Referring to thejdrawings:

F gure. is a 4 e pla e q y d agram re ating to h ype o s ua e a e pr ducedbr tfigeercircuit ofthe multivibrator. tyn

vFig r 2 is a wiring ia ram 41 9. .1. madm n tion of the invention,

Figure ,3 is a wiring diagramof another cation .of the. invention, and

Fi u 4 llu at h u the i ven i ii in co n c i n wit s ra s es eftubes adapted; o s pe th p s s to-aio uita le io .r. y lg acounter.

As indicated by Figure 1, thesduare. wave. pro: e ed y' a iaar circu tl m lt ibfa s'm typehas atone of its-ends a slope which extends. ve a tim i t a u ing ll s thepulses o th u e -.-may-n h passedh ueh t e ate to the W mer: c n be s e t at ou t ng pu ses of veryz ieh irequencies a nam her c rulse may a l 4 rcachhet i ras he pulse count i e 'i de s ditherre ue o t since ncre sednecount is registered by the counter. This difficulty is avoided by the switching device of Figure 2.

The switching device of Figure 2 includes a triode I0, a gas tube II to the control grid l2 of which a start pulse 13 of positive polarity is applied, and a gas tube [4 to the control grid 15 of which a stop pulse 16 is applied. All three of these tubes are biased off so that they do not conduct current. The output of the triode is applied to the grid 2l of an inverting tube 22 and the inverted output is applied to the common anode terminal 23-of a trigger circuit 25-45.

The application of the positive start pulse 13 to the grid 12 causes the tube H to draw current thus making the grid l1 more positive due to the voltage drop across the resistor 18-19 As a result the pulses 20 to be counted are transmitted through the triode to the grid 2i of the inverter tube 22 which is normally biased oil but is made conductive in response to each of the positive pulses 20'. These pulses are inverted by the tube 22 and reach the first trigger circuit 24 25 of the counter in the form of the negative pulses 20' Y The application of the stop pulse 16 of positive polarity to the grid causes the tube [4 to draw more current through a resistor 26 which is connected in the anode lead of the triode I0. As a result, the anode 21 of the tube I0 is made more negative by the voltage drop of the resistor 26 and the transmission of the pulses 20 through the triode I0 is interrupted.

It will be noted that the start pulse [3 and the stop pulse 16 both reach the common anode terminal 23 of the first trigger circuit 24 25 of the counter in the form'of a positive pulse and therefore produce no effect on the counter for the It is apparentthat the tubes II and I4 respond to the start and stop pulses substantially instantaneously and that they continue to conduct current until their anode potential is interrupted.-

For resetting the switching device in a standby condition with the tubes II and I4 not conducting and with current in the right hand triodes ofthe trigger circuits of the counter, the reset switches 29 and 30 may be opened and closed. These two switches may be ganged together so that'this resettingof the device is accomplished by a. single operation.

In the modification of Figure 3, the triode I0 of Figure 1 is replaced by a tetrode 3! and the stop pulselfi isapplied through the tube 14 to the screen grid 32 of this pentode. This modification, like that of Figure 1, isolates the counter from the switching pulses so that only the pulses to be counted are registered on the counter. Thus in the case of Figure 3 (1) the start pulse is made of such magnitude as to raise the potential of the grid 33 of the tetrode a value just below cutoil potential so that the start pulse does not appear in the output of the tetrode, (2) the pulses to be counted are inverted by the tetrode and applied directly to the common anode terminal 23 of the trigger circuit 2425 and (3) the stop pulse causes the tube M to draw current through a resistor 34 thus making the grid 32 more negative, interrupting the current of the pentode 3| and producing at the terminal 23 a positive pulse which has no efiect on the count registered in the counter.

The gaseous electron discharge devices H and It may be connected at various places along the amplifier stages by which the pulses are shaped to a form suitable to be registered by the counter as indicated by Figure 4. Thus the tube l i may operate in response to a start pulse as in the modification of Figure l to control the input to the three shaping stages 35, 36 and 31, and the tube l4 may function likewise in response to a stop pulse to interrupt the transmission of the counted pulses through the stage 31.

What the invention provides is an electronic switch which is substantially instantaneous in action due to the rapid response of the gaseous electron discharge elements which function to open and close the gate through which the transmitting circuit is completed.

I claim as my invention:

A high speed switching device including means for applying an operating potential, first and second gaseous conduction devices each having anode, cathode and grid electrodes, an electron discharge tube having anode, cathode and grid electrodes, a tapped resistor connected to the cathode of said first device, the grid of said electron discharge tube being connected to one of said resistor taps, a first anode load resistor connecting the anode of said'first device with said operating potential applying means, a second anode load resistor connecting said second device anode and said electron discharge tube anode to said operating potential applying means, means for applying signals to said electron discharge tube grid, means for applying a start pulse to said first device grid to render it conductive whereby said electron discharge tube transmits said signals and means for applying a stop pulse to said second device grid to render it conductive whereby transmission by said electron discharge device is stopped.

IGOR E. GROSDOFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,089,432 Roys et al Aug. 10, 1937 2,099,065 Holden Nov. 16, 1937 2,147,472 Ulrey Feb. 14, 1939 2,173,164 Hansell Sept. 19, 1939 2,221,569 Berkey et al Nov. 12, 1940 2,332,300 Cook Oct. 19, 1943 2,350,008 Artzt May 30, 1944 2,369,659 Carr Feb. 20, 1945 2,396,395 Smith et al May 12, 1946 2,403,873 Mumma July 9, 1946 2,403,918 Grosdoff July 16, 1946 2,405,597 Miller Aug. 13, 1946 2,411,648 Brauer et a1. Nov. 26, 1946 2,415,870 Ryder Feb. 18, 1947 2,428,990 Rajchman Oct. 14, 1947 FOREIGN PATENTS Number Country Date 487,982 Great Britain June 29, 1938 

